"Feeling the Blues": A Case of Calcium Channel Blocker Overdose Managed With Methylene Blue

Amlodipine is a dihydropyridine calcium channel blocker (CCB) commonly used to treat hypertension. In the United States, approximately 9,500 cases of CCB intoxication due to deliberate or inadvertent overdose were reported to poison centers in 2002. We present a case of a patient who presented with CCB overdose complicated by acute respiratory distress syndrome (ARDS) and recalcitrant shock all of which resolved with methylene blue therapy. We present a case of a 56-year-old African American woman who presented to the emergency department (ED) after intentional ingestion of large amounts of multiple pills likely consisting of cyclobenzaprine, amlodipine, losartan, and ibuprofen following an argument with her boyfriend. Treatment included insulin drip, 10% dextrose, and norepinephrine drip which was titrated up. First insulin drip and 10% dextrose were titrated up; however, vasopressor-resistant hypotension persisted, and the decision was made to administer methylene blue. Over 9,500 cases of CCB toxicity were reported to poison centers in the US in 2002. Although no definitive treatment is outlined, first-line therapy consists of IV calcium, high-dose insulin, and vasopressor support with either norepinephrine or epinephrine. Traditionally, methylene blue is used for methemoglobinemia and in cardiothoracic ICUs for post coronary artery bypass vasoplegia. It acts by selectively inhibiting nitric oxide-activated cyclic guanylate cyclase leading to decreased vasodilation of arteriolar smooth muscles improving vascular tone and systemic vascular resistance. In severe amlodipine overdose, experimental models demonstrate methylene blue improves HR and mean arterial pressure (MAP), improving survival rate. With few adverse side effects (green-tinged discoloration of urine, saliva, tears, and bodily fluids), methylene blue should be explored and implemented in the treatment of CCB overdose with refractory hypotension and ARDS.